To improve a network transmission capacity, a demand of introducing a wavelength division multiplexing (WDM) technology to metropolitan-area access and a data center is increasingly urgent. By means of the WDM technology, a transmission capability of a single optical fiber can be exponentially increased, and a wavelength dimension is introduced to network management and planning. In a WDM network, a distributed feedback laser (DFB) is usually used to transmit a wavelength signal. However, various signals of different wavelengths are needed in the WDM network, and each type of DFB laser transmits signals of a fixed wavelength. Therefore, the WDM network needs to include optical transceiver modules of DFB lasers that transmit signals of different wavelengths. Consequently, types of optical transceiver modules are increased, resulting in increased costs during good preparation, installation, operation and maintenance. In the prior art, a wavelength tunable laser is used to replace a fixed-wavelength DFB laser. A principle of the wavelength tunable laser is tuning a wavelength based on a Vernier effect of two groups of comb filters. A main implementation solution of the comb filter is etching a Distributed Bragg Reflector (DBR) on a semiconductor laser. By means of a wavelength tunable laser, not only types of optical modules can be reduced, but also additional flexibility is brought to network management and planning.
The prior art has at least the following problems: because a fine manufacturing process is required in manufacturing of the DBR grating, manufacturing costs of a DBR tunable laser are higher than costs of a common DFB laser. In addition, to tune a wavelength, a wavelength tunable laser needs complex multi-electrode current control and a control algorithm. This increases a manufacturing complexity rate, and further increases costs of the DBR tunable laser. Therefore, costs of a wavelength tunable laser-based WDM system cannot be radically reduced.